High Data Rate (HDR) is an emerging mobile wireless access technology that enables personal broadband Internet services to be accessed anywhere, anytime (see P. Bender, et al., “CDMA/HDR: A Bandwidth-Efficient High-Speed Wireless Data Service for Nomadic Users”, IEEE Communications Magazine, July 2000, and 3GPP2, “Draft Baseline Text for 1xEV-DO,” Aug. 21, 2000). Developed by Qualcomm, HDR is an air interface optimized for Internet Protocol (IP) packet data services that can deliver a shared forward link transmission rate of up to 2.46 Mbit/s per sector using only (1×) 1.25 MHz of spectrum. Compatible with CDMA2000 radio access (TIA/EIA/IS-2001, “Interoperability Specification (IOS) for CDMA2000 Network Access Interfaces,” May 2000) and wireless IP network interfaces (TIA/EIA/TSB-115, “Wireless IP Architecture Based on IETF Protocols,” Jun. 6, 2000, and TLA/EIA/IS-835, “Wireless IP Network Standard,” 3rd Generation Partnership Project 2 (3GPP2), Version 1.0, Jul. 14, 2000), HDR networks can be built entirely on IP technologies, all the way from the mobile Access Terminal (AT) to the global Internet, thus taking advantage of the scalability, redundancy and low-cost of IP networks.
An EVolution of the current 1xRTT standard for high-speed data-only (DO) services, also known as the 1xEV-DO protocol has been standardized by the Telecommunication Industry Association (TIA) as TIA/EIA/IS-856, “CDMA2000 High Rate Packet Data Air Interface Specification”, 3GPP2 C.S0024-0, Version 4.0, Oct. 25, 2002, which is incorporated herein by reference. Revision A to this specification has been published as TIA/EIA/IS-856, “CDMA2000 High Rate Packet Data Air Interface Specification”, 3GPP2 C.S0024-A, Version 2.0, June 2005, but has yet not been adopted. Revision A is also incorporated herein by reference.
FIG. 1 shows a 1xEV-DO radio access network 100 with radio node controllers 102 and 104 connected to radio nodes 108, 110, 112, 114, 116, 118 over a packet network 122. The packet network 122 can be implemented as an IP-based network that supports many-to-many connectivity between the radio nodes and the radio node controllers. The packet network is connected to the Internet 124 via a packet data serving node (PDSN) 106. Other radio nodes, radio node controllers, and packet networks (not shown in FIG. 1) can be included in the radio access network. The packet network 122 may be several distinct networks connecting individual radio node controllers to their associated radio nodes, or it may be a single network as shown in FIG. 1, or a combination.
Typically, each radio node controller controls 25-100 radio nodes and each radio node supports 1-4 carriers each of 1.25 MHz of bandwidth. A carrier is a band of radio frequencies used to establish airlinks with access terminals. The geographic area of the radio access network that is served by any given radio node is referred to as a cell. Each cell can be divided into multiple sectors (typically 3 or 6) by using multiple sectorized antennas (the term “sector” is used both conventionally and in this document, however, even when there is only one sector per cell).
Access terminals 120 communicate with the network 100 over airlinks 126. Each access terminal may be a laptop computer, a Personal Digital Assistant (PDA), a dual-mode voice/data handset, or another device, with built-in 1xEV-DO Rev-0 or Rev-A support. The airlink 126 between the network 100 and an access terminal 120 includes a control channel over which a serving radio node controller (i.e., the radio node controller on which a 1xEV-DO session of the access terminal 120) transmits messages and parameters that the access terminal 120 may need for access and paging operations. The messages and parameters (collectively referred to in this description as “control channel messages”) convey system parameters, access parameters, neighbor lists, paging messages, and channel assignment information to the access terminal 120.
Access terminals 120 periodically send route update messages to the network 100. Each route update message identifies the sectors that are “visible” to the access terminal 120. The visible sectors may include sectors of radio nodes that are not controlled by the access terminal's serving radio node controller.
When a packet destined for an access terminal 120 is received at the serving radio node controller 102, the serving radio node controller 102 selects a set of sectors on which the access terminal 120 is to be paged, and sends a paging message to the selected sectors over respective control channels. One selection method known as “flood paging” involves selecting the sectors of all of the radio nodes that are controlled by the access terminal's serving radio node controller. Another selection method known as “selective paging” involves selecting only the visible sectors (or a subset of the visible sectors) of radio nodes that are controlled by the access terminal's serving radio node controller.
In a scenario in which the access terminal is located at or near the border of two sectors, both of which are visible to the access terminal but only sector A is controlled by the access terminal's serving radio node controller, the network is limited to sending paging messages, UATI_Assignment messages, and/or TrafficChannelAssignment messages to the access terminal over the control channel of the single sector A.
In a scenario in which an active access terminal crosses over the border between two sectors that are on different carriers and/or subnets, an inter-carrier and/or inter-subnet hard handoff is performed between the radio node controller's controlling the radio nodes associated with the two sectors. The user disruption associated with such hard handoffs are generally in the order of 5-10 seconds.
In both scenarios, lower success rates are generally associated with the activities (e.g., paging, UATI assignment, traffic channel assignment, and hard handoffs) that take place when an access terminal is located at or near a carrier and/or subnet boundary.